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PSU 230v in 12v DC out 60 amps+

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rithym

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Hi to all
Would like to make a cheap bench power supply that works from a standard 230v 13amp socket but pushes out 12v DC 60 amps+
I can get my hands on a MIG welder which has a large transformer inside unfortunately the output is 14v AC 130amp which would do the job nicely if I could convert the AC to DC. Any ideas would be greatly appreciated

TIA
 
You can get a bridge rectifier, but they are quite expensive at that power.

There will be a lot of output ripple, and to smooth that sort of current will need a huge capacitor.

What is the current for? 60 A isn't for a general purpose bench supply.
 
Hi & thanks for the reply

I am playing with a sick 12v air con system on the roof of our motor home the 12v dc motor that runs the compressor pulls about 45 amps plus there are some cooling fans hence the need for 60 amp. I want to be able to feed the unit with a strong 12.6v supply so I can re gas it and make sure the unit is actually in good order before I go much further buying new leisure batteries, bigger cables, etc.
 
Just stack a few 20 - 30 amp battery chargers together and put a big capacitor or set of large capacitors on them to smooth out the output.
 
Just stack a few 20 - 30 amp battery chargers together and put a big capacitor or set of large capacitors on them to smooth out the output.
A 12V lead-acid battery makes a very good capacitor for this purpose. It will also provide any large starting currents that the motor may require.
 
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OK so if I am correct in my understanding I can attach 3 x 20 amp battery chargers in parallel to a 12v leisure battery (which I already have) plug the chargers into the mains and these will in effect give me 60 amp 12v DC? If it's that simple i'm halfway there as I already have 1 x 30 amp charger and a 15 amp charger, sure I can borrow a 20 amp from a neighbor is it ok to mix the ampages?
 
Shouldn't be much of a problem with mixing them. Normally a battery charger has a slight pull down on its output voltage so they should tend to average themselves out to what ever their individual design capacity is.

Depending on what ranges they have you should be able to adjust each of them to work within there design capacities.
 
OK so if I am correct in my understanding I can attach 3 x 20 amp battery chargers in parallel to a 12v leisure battery (which I already have) plug the chargers into the mains and these will in effect give me 60 amp 12v DC? If it's that simple i'm halfway there as I already have 1 x 30 amp charger and a 15 amp charger, sure I can borrow a 20 amp from a neighbor is it ok to mix the ampages?
That should work.

And there should be no problem in mixing amperages. Each charger will just deliver the amps it can.
 
OK been doing the neighborly hunt for another big charger nobody has anything above 6 amp so i'm thinking surely if I only want to test for 20 mins. at a time will the leisure battery itself not supply the extra amps if I connect my 30 amp and 15 amp in parallel? I can keep the DC cable length from battery to air con unit down to .5 meter or less if I lug all the stuff up on the motor home roof (battery, 2 x chargers and extension lead)
Could be a great firework display for the locals if it all goes wrong :)
 
OK been doing the neighborly hunt for another big charger nobody has anything above 6 amp so i'm thinking surely if I only want to test for 20 mins. at a time will the leisure battery itself not supply the extra amps if I connect my 30 amp and 15 amp in parallel? I can keep the DC cable length from battery to air con unit down to .5 meter or less if I lug all the stuff up on the motor home roof (battery, 2 x chargers and extension lead)
Could be a great firework display for the locals if it all goes wrong :)
Should work depending upon the Ah rating of the battery. The battery would have to supply about 15A with the two chargers connected, so divide the Ah rating of the battery by 15 to see the maximum time you can run (but you probably don't want to run that long since, unless it's a deep cycle battery, it's not good to completely discharge the battery). Running for 20 minutes would consume about 5Ah.

Edit: Regarding the fireworks, just make sure all polarities are correct and don't accidentally short the battery. Lead-acid batteries make good arc welders.
 
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Batteries are 110 Ah leisure type not true deep cycle traction (like in golf carts or fork lifts). The cable run from where the batteries are fixed in the motor home up to the roof is approx. 7 meters that may be the problem i'm not sure the cables are big enough to carry the DC current required, hence the need for a power pack close to the unit on the roof. If I can carry out the test and the air con works okay after re gassing then I can tackle the problem of how to get more current from the leisure batteries up to the roof. Probably end up doubling up the present cable if there's enough room. **broken link removed** do a nice 60 amp charger/ power pack which will supplement the leisure batteries nicely when hooked up to mains or generator but I didn't want to spend that kind of money if the air con unit, etc was not up to the job which presently it's not.
 
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